1. Technical Field
The present invention relates to a liquid crystal device and electronic equipment.
2. Related Art
In recent years, a display system with electronic polarization using an electro-optic effect is proposed. The electro-optic effect is a phenomenon in which the refractive index of a substance is changed by an external electric field. For example, Kerr effect is known as the electro-optic effect. The Kerr effect indicates a phenomenon in which when an electric field is applied to an isotropic polar substance, the birefringence which is proportional to the square of the electric field strength with the direction of the electric field as an optical axis is excited. As a liquid crystal material which develops such Kerr effect, a blue phase is known. The blue phase, being an optically isotropic liquid crystal phase which appears in a specific temperature range between a chiral nematic phase and an isotropic phase, is referred to as the blue phase since it often appears visually in blue, and is known in that the response speed is significantly high. Since the development temperature range of the blue phase is very narrow, attempt is made to enlarge the development temperature range by introducing high-polymer materials therein (See JP-A-2005-336477, for example).
In recent years, the liquid crystal device is widely used as a display unit of mobile electronic equipment such as mobile phones or mobile information terminal. In general, a transflective type, which provides reflective display and transmissive display, is employed for the liquid crystal device used in the mobile electronic equipment, and improvement of the visual field angle is achieved by further employing the lateral electric field system. Therefore, the high-speed response is achieved by using the blue phase in the transflective liquid crystal device of such lateral electric field system.
In general, in the transflective liquid crystal device, in order to obtain a preferably display both in the reflective display and the transmissive display, a structure for differentiating the cell thickness (thickness of the liquid crystal layer) between the reflective display area and the transmissive display area in the dot area (so-called multi-gap structure) is generally employed. However, since the blue phase cannot change the alignment of liquid crystal only in a local area in which the electric field is generated, when the cell thickness exceeds a predetermined value, the electric field does not reach the entire liquid crystal molecule, and hence the corresponding area does not contribute to brightness. Therefore, it is no longer necessary to form the multi-gap in the transflective area. However, when white display (for example, the phase difference of λ/4) is achieved in the reflective area, the phase difference in the transmissive area is λ/4, and hence the brightness is not sufficient. Therefore, the phase differences of the refractive index (retardation) do not match between the transmissive display area and the reflective display area, and hence the contrast of display is disadvantageously lowered.